The present invention relates generally to a method of and an apparatus for measuring accurately the shape of a particular part or all of an object, particularly to a method of and an apparatus for measuring the section profile of a tire without contacting the surface of the tire, by measuring continuously the profile of the tire with a camera and a non-contact type slit ray profile detective sensor in order to eliminate the dead angle that occurrs in the measuring of the profile, thereby to increase its accuracy and speed in 3-dimensional measuring.
In general, even when any particular object is measured by using a conventional contact-type shape detective sensor, if the object is a relatively hard solid, measurement errors do not occur, but if the object is semi-solid, or in case the original shape of the object is deformed by contacting the sensor on the surface of the object, a considerable error results. In case the shell profile of a tire having a side wall and tread is measured, said contact-type sensor can not dispense with some error in the measurement itself. Even though the existing non-contact types of measuring apparatus are used to determine 3-dimensional coordinate values, the measurement must be made several times, and in tedious repetition with the use of various implements with the results being compared with each other, and yet no escape from some errors.